This application claims the priority of 198 41 828.0-22, filed Sep. 12, 1998, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a hybrid drive, in particular for vehicles, and more particularly, to a hybrid drive containing at least one first electric machine, which can be operated at least as an electric motor; a second electric machine, which can be operated at least as an electric motor and has a nonrotatably arranged stator and a rotor which can be rotated relative to the latter; a variable-ratio gear unit which has a primary-motor input component, which is connected or can be connected to a primary motor, a machine input component, which is connected or can be connected to the rotor of the second electric machine, and an output component, all three parts being arranged so as to be rotatable relative to one another.
A hybrid drive is described in DE-A-24 36 546. In this known drive, a primary motor is connected to a planet carrier of a simple planetary gear unit. The annulus is connected to an output shaft on which a rotor of a second electric machine (motor/generator) is arranged in a rotationally rigid manner. The stator of this machine is arranged nonrotatably in a fixed location.
A central sun gear of the planetary gear unit is connected to a rotor of a first electric machine (motor/generator) in this known drive, the stator of which is likewise arranged nonrotatably in a fixed location. That component (planet carrier) of the planetary gear unit which is connected to the primary motor can be connected directly to the output shaft by a clutch. Depending on the mode in which the hybrid drive is being driven, the two electric machines can each operate as an electric motor or an electric generator. DE-A-41 24 479 and DE-A-197 17 884 describe the same kind of hybrid drive.
In another kind of hybrid drive described in JP-A-09175199, a primary motor is connected to the central sun gear of a simple planetary gear unit. The annulus is connected to an output shaft which is connected in a rotationally rigid manner to the rotor of a second electric machine (motor/generator), the stator of which is arranged nonrotatably in a fixed location. The planet carrier of the planetary gear unit is connected with a rotor of a first electric machine (motor/generator). The stator is likewise arranged rotatably and is connected in a rotationally rigid manner to the sun gear. DE-A-44 07 666 describes a hybrid drive for vehicles with a primary motor arranged in series and two electric machines (motor/generator). A clutch can be used to form a mechanical connection from the primary machine, via the two electric machines, to an output shaft in order to drive the latter without slip in the electric machines.